This invention relates to a three point hitch for connecting an implement to a tractor.
Currently available three point hitch systems require two people to connect implements to a tractor. One person drives the tractor and one person on the ground attaches the two lower arms which require a precise alignment. With two people, one hitch arm can be attached and then with a slight forward or backward movement of the tractor, the other arm is attached. For one person to attempt to attach a tractor to a three point hitch implement, the task becomes onerous requiring a lot of back and forth movement of the tractor and much mounting and dismounting to and from the tractor seat. With one hitch arm attached and one hitch arm loose, hitching can become very dangerous should the tractor move and the operator get caught between the tractor and the implement.
The upper center arm is just as precise to attach as the two lower arms. It has to be readjusted in length every time a different implement is used. This becomes very time consuming because typically it is extended and retracted by manually screwing a turnbuckle in or out.
Efforts to solve these problems have resulted in a variety of aftermarket designs which require the purchase and use of an additional intermediate devices that are attached to the tractor to facilitate its connection with various implements.
U.S. Pat. No. 2,688,865 discloses a hand operated hydraulic lock for locking the trunk compartment of a motor car and is it not applicable to a attachment of implements to a tractor.
U.S. Pat. No. 3,312,478 is a very complex intermediate device with many moving parts and chains and offers as much of a attaching problem as those presented by conventional implement hitches.
U.S. Pat. No. 3,434,737 offers an intermediate hitching device with an excessive number of parts requiring manual adjustment in order to hitch an implement to a tractor.
U.S. Pat. No. 3,561,789 solves part of the problems of attaching tractor to implement but still uses a hitch adaptor as an additional device between tractor and the implement and is of a complex design.
U.S. Pat. No. 4,125,271 relates to a tool suspension for either front or rear mounting of tools from vehicles in the form of a three point suspension for hydraulic lifting and lowering. Front and rear mounted tools are used on motor vehicles for road maintenance, snow clearing, street cleaning and grass cutting. No adaptation was found for use with farm implements.
U.S. Pat. No. 5,029,650 discloses an intermediate frame mounted on the tractor hitch links.
U.S. Pat. No. 5,743,339 discloses a two part steel plate device. One plate is attached to the three point hitch of the tractor and the other plate is attached to the implement. Steel plate of a size and strength to accomplish the task would be very heavy. Another drawback to this system is that there are no provisions for the fore and aft adjustment of the upper link. A still further problem is a matching plate would have to be purchased for each implement used. This represents a substantial investment for the operator.
U.S. Pat. No. 5,975,215 is a low profile transferable hydraulic three point hitch designed for use on the front or rear of a truck. The truck can then be used to attach to three point implements instead of using a tractor.
U.S. Pat. No. 5,997,024 illustrates a hitching mechanism for tractors to aid in steering the implements in specific agricultural uses such as in a track laying application where both a steering function and a lateral shifting capability in needed. This is a specialized function and not needed for general use of tractors and implements.
It is an important object of the invention to provide a power operated tractor hitching system which can be readily aligned and secured to an implement without the operator leaving the tractor seat and without the use of intermediate devices.
It is a further object of the invention to provide an improved three point hitch which is economical to manufacture, permits quick attachment of the implement and provides long trouble free service.
The invention solves the problems present in prior implement hitch designs by a redesign of the tractor hitch so as to eliminate the need for intermediate hitch devices. The ends of the hitch arms are redesigned and controls added to permit the operator to hitch the tractor to an implement without dismounting from the tractor seat. The tractor is easily and quickly hitched to an implement by one person in a safe manner. The weight and expense of intermediate hitch devices is avoided.